Preheat the oven to 400 °F
Line a baking sheet with parchment paper, or lightly spritz a foil-lined baking sheet with nonstick spray.
In a bowl, toss together the cauliflower florets, sweet potato cubes and olive oil.
Spread the cauliflower and sweet potatoes evenly on the prepared baking sheet and put it in the oven to roast for 30 minutes. You'll want to stir the vegetables around once, at the 15-minute mark.
When the veggies are done roasting, turn the oven down to 375 °F
Whisk together the eggs, egg whites, sour cream, mustard, paprika, chives salt, and pepper.
Heat a skillet over medium heat on the stovetop and give it a good spray of nonstick spray.
Arrange the roasted veggies and the gouda cheese in a skillet that will be able to withstand the oven @ 375 °F . You're going to put the whole thing into the oven, so no plastic, and no nonstick-coatings! Cast iron and stainless steel are both great.
Pour the egg mixture right on top of the cheese and vegetables and just leave it there, let it cook for about 5 minutes. (You might want to reach in with a fork to make sure the cheese, potatoes and cauliflower are all evenly distributed.)
After 5 minutes, put the pan in the preheated oven and let it cook at 375 °F for about 10 to 12 minutes, until the frittata is set all the way through.
OMG, DON'T FORGET TO TREAT THE SKILLET LIKE ANY OTHER HOT DISH THAT WAS JUST IN THE OVEN! Don't make the mistake of touching the handle without an oven mitt or a dishpad, right? I've made this mistake far too many times.